I wear my drysuit sometimes for protection from the elements even when sailing with 75 degree air temperature in the Keys (starting the Tybee 500). In warmer air temps, under the drysuit I wear a very thin silk suit (I know...I'm going to get it for this one - Bonnie calls it my superhero outfit) and a pair of shorts...the silk functions as a lightweight rash guard with no real insulation. Then as the water and weather get cooler, I keep the silk layer but start to add insulation. I'll graduate to a thin fleece top, then add thin fleece bottoms, then thicker fleece top, and then thicker fleece bottoms. I do get warm standing on the beach waiting for the start but usually get comfy once the suit gets a little damp and there's a little breeze. Only once or twice have I felt slightly overheated and that was usually after a burst of activity like paddling through the surf.